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Background: Defective intestinal epithelial tight junction (TJ), characterized by an increase in intestinal TJ permeability, has been shown to play a critical role in the pathogenesis of inflammatory bowel disease (IBD). Tumor necrosis factor-α (TNF-α) is a key pro-inflammatory cytokine involved in the immunopathology of IBD and has been shown to cause an increase in intestinal epithelial TJ permeability. Although TNF-α antibodies and other biologics have been advanced for use in IBD treatment, these therapies are associated with severe side effects and have limited efficacy, and there is an urgent need for therapies with benign profiles and high therapeutic efficacy. Probiotic bacteria have beneficial effects and are generally safe and represent an important class of potential therapeutic agents in IBD. Lactobacillus acidophilus (LA) is one of the most used probiotics for wide-ranging health benefits, including in gastrointestinal, metabolic, and inflammatory disorders. A specific strain of LA, LA1, was recently demonstrated to have protective and therapeutic effects on the intestinal epithelial TJ barrier. However, the mechanisms of actions of LA1 remain largely unknown. Methods: The primary aim of this study was to investigate microbial-epithelial interactions and novel signaling pathways that regulate the effect of LA1 on TNF-α-induced increase in intestinal epithelial TJ permeability, using cell culture and animal model systems. Results and Conclusion: Pre-treatment of filter-grown Caco-2 monolayers with LA1 prevented the TNF-α-induced increase in intestinal epithelial TJ permeability by inhibiting TNF-α-induced activation of NF-κB p50/p65 and myosin light chain kinase (MLCK) gene and kinase activity in a TLR-2-dependent manner. LA1 produced a TLR-2- and MyD88-dependent activation of NF-κB p50/p65 in immune cells; however, LA1, in intestinal cells, inhibited the NF-κB p50/p65 activation in a TLR-2-dependent but MyD88-independent manner. In addition, LA1 inhibition of NF-κB p50/p65 and MLCK gene was mediated by TLR-2 pathway activation of phosphatidylinositol 3-kinase (PI3K) and IKK-α phosphorylation. Our results demonstrated novel intracellular signaling pathways by which LA1/TLR-2 suppresses the TNF-α pathway activation of NF-κB p50/p65 in intestinal epithelial cells and protects against the TNF-α-induced increase in intestinal epithelial TJ permeability.

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Siderophores produced by microorganisms to scavenge iron from the environment have been shown to contribute to virulence and/or stress resistance of some plant pathogenic bacteria. Phytopathogenic bacteria of Pectobacterium genus possess genes for the synthesis of siderophore enterobactin, which role in plant-pathogen interactions has not been elucidated. In the present study we characterized the phenotype of the mutant strain of Pba deficient for the enterobactin-biosynthetic gene entA. We showed that enterobactin may be considered as a conditionally beneficial virulence factor of Pba. The entA knockout did not reduce Pba virulence on non-primed plants; however, salicylic acid-primed plants were more resistant to ΔentA mutant than to the wild type Pba. The reduced virulence of ΔentA mutant towards the primed plants is likely explained by its compromised resistance to oxidative stress.

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Rapid development of antibiotic resistance in bacteria is a critical public health problem in the world. One of the main routes of resistance development is the transfer of genes containing antibiotic resistance cassettes. Gene transfer can be done through horizontal transfer of genes: transduction, conjugation, and transformation. Many factors in the environment influence these processes, and one of them is the action of metal oxide nanoparticles (MONPs), which can appear in the milieu through both biological synthesis and the release of engineered nanomaterial. In this study, the effect of AlOOH, CuO, Fe3O4, TiO2, and ZnO MONPs on the transformation (heat shock transformation) of bacteria Escherichia coli K12, and the conjugation between E. coli cc118 and E. coli Nova Blue were studied. The MONPs were synthesized by one method and fully characterized. ZnO nanoparticles (NPs) have significantly increased the efficiency of transformation (more than 9-fold), while the other NPs have reduced it to 31 times (TiO2 NPs). AlOOH NPs increased the number of transconjugants more than 1.5-fold, while CuO and Fe3O4 NPs did not have a significant effect on transformation and conjugation. Thus, the data shows that different types of MONPs can enhance or inhibit different gene transfer mechanisms, affecting the spread of antibiotic resistance genes.

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Nowadays celiac disease is becoming more common. It is the autonomic genetic disease that is accompanied by damage to the intestines due to a reaction to eating some proteins. People who are suffering from celiac disease cannot eat food containing gluten, including dough made from gluten-containing seeds. But the gluten-free dough has commonly bad rheological properties and cannot be used for automatic molding the dumplings. In this article, we propose the ultrasonic-assisted technology to fabricate the gluten-free dough with improved rheological properties acceptable for automatic molding of the dumplings. Application of ultrasonic treatment at a frequency of 35 kHz during the dough preparation leads to the homogenization of the dough structure and changing the rheological properties of the dough. The ultrasound induces mechanical, physical and chemical/biochemical changes of the dough components through cavitation. The sonication causes a doubled dough volume increase followed by an additional mass yield of the dumplings equal 2-10% per kilogram of dough. Besides extra beneficial economic effect, our technology provides an additional sterilization effect of the fabricated dough.

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The lipopolysaccharide (LPS) of Herbaspirillum frisingense GSF30T (HfGSF30), a non-pathogenic diazotrophic endobiont, was isolated by phenol-water extraction from bacterial cells and was characterized by chemical analyses and SDS PAGE. The O-specific polysaccharide (OPS, O-antigen), obtained by mild acid hydrolysis of the LPS, was examined by sugar and methylation analysis, along with 1H and 13C NMR spectroscopy, including 2D 1H,1H COSY, 1H,1H TOCSY, 1H,1H ROESY, 1H,13C HSQC, and 1H,13C HMBC experiments. The OPS was found to consist of branched tetrasaccharide repeating units of the following structure: [Formula: see text] This structure is unique among the known bacterial polysaccharide structures. Analysis of the HfGSF30 genome showed that it contained a set of sequentially arranged operons (presumably a cluster of genes) associated with the O-antigen. Amino acid sequence analysis using the BLAST program demonstrated the specificity of this putative cluster for Herbaspirillum spp. The genes responsible for the biosynthesis of the OPS of HfGSF30 were dispersed in the genome, constituting small operons. A putative O-antigen gene cluster of HfGSF30 was identified and found to be consistent with the OPS structure.

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In the present study, we attempted to elucidate if the harmful phytopathogenic bacteria of Pectobacterium genus (P. atrosepticum) possess the enzymes for oxidation of phenolic compounds. Polyphenol oxidase (laccase) activity was revealed in P. atrosepticum cell lysates. Using bioinformatic analysis, an ORF encoding a putative copper-containing polyphenol oxidase of 241 amino acids with a predicted molecular mass of 25.9 kDa was found. This protein (named Pal1) shares significant level of identity with laccases of a new type described for several bacterial species. Cloning and expression of the pal1 gene and the analysis of corresponding recombinant protein confirmed that Pal1 possessed laccase activity. The recombinant Pal1 protein was characterized in terms of substrate specificity, kinetic parameters, pH and temperature optimum, sensitivity to inhibitors and metal content. Pal1 demonstrated alkali- and thermo-tolerance. The kinetic parameters Km and kcat for 2,6-dimethoxyphenol were 0.353 ± 0.062 mM and 98.79 ± 4.9 s-1 , respectively. The protein displayed high tolerance to sodium azide, sodium fluoride, NaCl, SDS and cinnamic acid. The transcript level of the pal1 gene in P. atrosepticum was shown to be induced by plant-derived phenolic compound (ferulic acid) and copper sulfate.

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